In a mobile communication system having been studied as “Evolved universal terrestrial radio access network (E-UTRAN)”, a mobile station is configured as follows. In a case where, in communicating in a certain cell, a mobile station reselects a cell satisfying a required quality (Cell Reselection) within a predetermined period after failing in detection of a radio link with a radio base station which manages the certain cell (Radio Link Failure), the mobile station transmits a connection re-establishment request signal to a radio base station which manages the cell reselected by the mobile station.
The aforementioned mobile communication system, however, has the following problems.
When holding setting information (UE Context) related to the mobile station, the radio base station having received the connection re-establishment request signal transmitted by the mobile station as described above continues the communication currently performed by the mobile station, in response to the connection re-establishment request signal. On the other hand, the radio base station rejects the connection re-establishment request signal, when not holding the setting information (UE Context) related to the mobile station.
In addition, when it is determined that only a cell (Inter-RAT cell) using a radio access scheme different from that of the certain cell has been reselected within the predetermined period after the occurrence of the foregoing “Radio Link Failure”, the setting information (UE Context) related to the mobile station is not held in the “Inter-RAT cell”. Therefore, the mobile station is configured to delete the setting information (UE Context) related to the mobile station.
Consequently, as described above, when the mobile station transmits the connection re-establishment request signal to the radio base station not holding the setting information (UE Context) related to the mobile station, the radio base station rejects the connection re-establishment request signal. Accordingly, a radio connection for communication performed by the mobile station is disconnected, and a user himself/herself needs to perform a connection recovery procedure manually, resulting in a problem of deteriorating serviceability.
Moreover, similarly, when only an “Inter-RAT cell” has been reselected within the predetermined period after the occurrence of the “Radio Link Failure”, a user himself/herself needs to perform the connection recovery procedure manually, resulting in the problem of deteriorating serviceability.